This invention concerns a rope clamp in shape of a sleeve or a ferrule with a sleeve-shaped part of plastic malleable material, which sleeve or sleeve part is made to be pressed firmly around one or several rope parts.
Rope clamps of such kind are applied to ropes in several manners. For instance the connection can be made by pressing of the whole sleeve length simultaneously or by pressing in sections or by rolling longitudinally of the sleeve. The pressing can be made with one or several rope parts inserted in the sleeve and independently if the sleeve consists of the sleeve part, which at one end turns into a fork, tap or some other part. The method of pressing sleeves on to ropes sectionwise is time-wasting and complicated. It requires in addition to this the utmost exactitude to obtain a good result. The application by rolling has disadvantages as the sleeve easily gets banana-shaped with the consequence that the solidity of the rope connection is reduced at straight load by this shape.
The pressing of a cylindrical sleeve or sleeve-shaped part around a rope simultaneously in one stage over the whole sleeve length is also connected with disadvantages. When pressing the sleeve together there is an accumulation of excess in the middle zone of the sleeve while there is no such accumulation at the sleeve ends as the material there has the possibility to flow in the axial direction. The rope part or the rope parts, therefore, are subject to the highest compression strain in the middle zone of the rope sleeve and to a lesser extent at the end parts of the sleeve. This means that there is an undesirable irregular pressure distribution in the rope clamp. The longer the sleeve or the sleeve-shaped part is, which is to be pressed in one stage, the more difference there will be between the pressure strain in the mentioned middle zone and the end parts of the sleeve.
When using ferrules for only one rope part in contrast to what is the case when making a loop, the load is transferred entirely from the rope to the clamp as the rope is inserted only at one end of the ferrule. In such a case the sleeve-shaped part has to be extremely long especially if the rope is formed of thin wires on its surface. This makes the above mentioned problem with different flows of the material in different parts of the sleeve part during the compression and consequently the irregular pressure distribution in the rope clamp especially obvious.